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United States Patent |
6,158,296
|
Denance
|
December 12, 2000
|
Transmission with structurally simplified gear ratio
Abstract
A transmission (1) comprising a gear assembly for transmitting a rotary
motion from a driving shaft (2) to a driven shaft (3), with variable gear
ratio, the two shafts (2 and 3) not being coaxial. This transmission
consists in: a gear-wheel (4) axially split into two half-gear-wheels (5
and 6) one (5) axially mobile relative to the other (6) and also relative
to one of the shafts (3) supporting them, the two half-gear-wheels (5 and
6) being fixed in rotation relative to this shaft (3); a plate (7),
integral with the other shaft (2), comprising, on at least one of its
surfaces, several gear teeth, concentric (8 to 11) with this shaft (2),
cooperating with the gear-wheel (4); and elements for axially displacing
the two half-gear-wheels (5 and 6) to alter the geared concentric tooth (8
to 11), thereby shifting the gear ratio. The invention is preferably
applicable to land vehicles.
Inventors:
|
Denance; Raymond (le Commodore H 41, Marina Baie des Agnes, F-06270 Villeneuve Loubet, FR)
|
Appl. No.:
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380962 |
Filed:
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October 27, 1999 |
PCT Filed:
|
March 14, 1997
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PCT NO:
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PCT/FR97/00458
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371 Date:
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October 27, 1999
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102(e) Date:
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October 27, 1999
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PCT PUB.NO.:
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WO98/41780 |
PCT PUB. Date:
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September 24, 1998 |
Current U.S. Class: |
74/351; 74/416; 74/450 |
Intern'l Class: |
F16H 003/30 |
Field of Search: |
74/393,395,416,446,447,448,450,351
475/196,197
|
References Cited
U.S. Patent Documents
619551 | Feb., 1899 | Ferris | 74/351.
|
682861 | Sep., 1901 | Rittman | 74/351.
|
767866 | Aug., 1904 | Busche | 74/351.
|
1188641 | Jun., 1916 | Formage | 74/351.
|
2033850 | Mar., 1936 | Roberts | 74/416.
|
2780110 | Feb., 1957 | Kopa | 74/416.
|
5251504 | Oct., 1993 | Summerville, Jr. et al.
| |
5467660 | Nov., 1995 | Barens | 74/351.
|
5496049 | Mar., 1996 | Escobedo | 74/351.
|
Foreign Patent Documents |
524666 | Sep., 1921 | FR | 74/351.
|
877.542 | Dec., 1942 | FR.
| |
2 742 203 | Jun., 1997 | FR.
| |
2 252 552 | May., 1974 | DE.
| |
624265 | Jun., 1949 | GB | 74/351.
|
2 263 953 | Aug., 1993 | GB.
| |
Primary Examiner: Marmor; Charles A
Assistant Examiner: Ho; Ha
Attorney, Agent or Firm: Young and Thompson
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This is the 35 USC 371 national stage of international application
PCT/FR97/00458 filed on Mar. 16, 1997, which designated the United States
of America.
Claims
What is claimed is:
1. A transmission comprising at least one gear adapted to transmit rotary
movement of a drive shaft to a driven shaft, of variable speed ratio, the
two shafts not being coaxial, a first of said shafts carrying a pinion,
and the second shaft carrying a plate;
the pinion being split axially into two half-pinions movable axially one
relative to the other and also relative to the first shaft which supports
said half-pinions, the two half-pinions being fixed in rotation relative
to said first shaft;
the plate having a plurality of surfaces, and being secured to the second
shaft, and comprising, on at least one of said surfaces, several tooth
sets concentric with said second shaft, which coact with the pinion; and
means for axially displacing the two half-pinions so as to change the
engaged concentric tooth set and thus alter the speed ratio.
2. The transmission according to claim 1, wherein the pinion comprises 2n
teeth, each half-pinion comprises n teeth, and each concentric tooth set
of the plate comprises a multiple of n teeth, n being a positive whole
number.
3. The transmission according to claim 2, wherein the distance separating
two adjacent teeth of the pinion, the two half-pinions being in the same
plane, is identical to the distance separating two adjacent teeth of a
same concentric tooth set of the plate.
4. The transmission according to claim 2, wherein the difference existing
between the number of teeth of two adjacent concentric tooth sets of the
plate is equal to n or to a multiple of n.
5. The transmission according to claim 1, wherein the plate comprises a
changing region for the concentric tooth set engaged by the half-pinions,
which is formed by alignments of two adjacent teeth of each concentric
tooth set, the two alignments being parallel and located on opposite sides
of an initial radius of the plate.
6. The transmission according to claim 5, wherein the distance separating
two adjacent teeth of a same alignment is constant.
7. The transmission according to claim 1, wherein the teeth of the pinion
have a spherical shape, and the teeth of the concentric tooth sets
comprise edges of transverse blind holes provided in at least one surface
of the plate.
8. The transmission according to claim 1, wherein the teeth of the pinion
have a spherical shape, and the teeth of the concentric tooth sets
comprise edges of transverse bores provided in the plate.
9. The transmission according to claim 1, wherein the first shaft, which
carries the axially movable pinion that is fixed in rotation relative to
said first shaft, is, in transverse cross-section, channelled over at
least the length of the first shaft coacting with the pinion, thereby
creating at least one groove ensuring the axial mobility and the
securement in rotation of each half-pinion of complementary shape relative
to the first shaft.
10. The transmission according to claim 9, wherein the transverse
cross-section of the first shaft of the pinion has an H shape, which is
constituted by a grooved square on two of opposite surfaces.
11. The transmission according to claim 1, wherein on opposite sides of a
plane formed by the pinion, said pinion extends in the form of two skirts
of a shape complementary to the first shaft.
12. The transmission according to claim 1, wherein the first shaft is a
drive shaft and the second shaft is a driven shaft.
13. The transmission according to claim 1, wherein the second shaft is a
drive shaft, and the first shaft is a driven shaft.
14. The transmission according to claim 1, wherein the axis of the shaft of
the pinion and of the plate are perpendicular and intersect.
15. The transmission according to claim 1, wherein the plate coacts with at
least one other pinion.
16. The transmission according to claim 15, wherein the transmission uses
two plates comprising blind holes disposed side by side and having open
free surfaces; and at least one pinion coacts with one of the surfaces and
at least one other pinion coacts with another surface.
17. The transmission according to claim 15, wherein at least one pinion
coacts with one of the surfaces of the plate, and at least one pinion
coacts with another surface of the plate.
18. The transmission according to claim 5, wherein upon changing the
concentric tooth set that is engaged, an axial plane, defined by one of
the half-pinions and by the other half-pinion, passes through the initial
radius of the plate.
Description
FIELD OF THE INVENTION
The present invention relates to a transmission with speed ratio change,
which is a very simple structure. This transmission is present in the form
of a simple gearing in its simplest version.
BACKGROUND OF THE INVENTION
The state of the art can be defined by the following documents.
The document WO-A-89/09895 has for its object an apparatus with gearing
which comprises a first gear element, as well as a second and a third gear
element engaging with said first gear element, such that the rotation of
the first gear element is transmitted to the second and third gear
elements, or such that the rotation of the second and third gear elements
is transmitted to said first gear element. Said first gear element
comprises assemblies of elongated gear teeth defining a portion of a
conical shape, the gear teeth, located in each assembly, being parallel to
each other, and several of said gear teeth in each assembly being of
different lengths. The second and third gear elements are connected such
that they turn at the same speed during operation of said gear apparatus.
Said second and third gear elements are movable along the gear teeth of
each assembly, so as to vary the gear ratio between the first gear element
and the second and third gear elements.
Although of novel structure, this apparatus is complex in structure, with a
very large number of moving parts. The use of a central cone, as a first
gear element, is consumptive of space. This volume is greater as the
number of ratios is greater. Finally, between the tooth assemblies, there
are smooth regions in which the engagement of the second and third gear
elements is not carried out; there is thus a differential force on the
teeth of these elements, which is not at all adequate for reliability of
the apparatus.
The document FR-A-2.640.342 discloses a speed varier, with gearing always
engaged, which is provided with a shaft (and its pinion, one or the other)
sliding parallel to the principal conical gearing, and by a cone
constituted of stacked toothed wheels which are not joined and by two
toothed spirals, one rising, the other descending, which cross without
interference of the teeth of the intervals thanks to their number and
specific dimensions and to their male shape (pinion) and female shape
(cone) such that the pinion engages, either in a circular trajectory
(speed ratios) without axial pressure on the shaft, or on the spirals
(with axial pressure), but not between the two. The figure represents the
projection on a plane of the principal conical gear, at the level of the
diameter of the foot. The beveled lozenges represent the impression of the
tips of the teeth of the pinion; the double concave bevel teeth are taken
en masse.
This device, like the preceding one, uses a cone constituted by stacked
toothed wheels, such that it is voluminous with many moving parts.
The document FR-A-877.542 provides a gear system having teeth constituted
by one or several rows of movable balls disposed in recesses provided on
primary diameters of independent bodies, engaging in corresponding
recesses or roller tracks provided in the primary diameters of the wheels,
pinions, or plates with which they are to be coupled.
The gear system proposed here requires the use of heavy and costly
equipment because the plate must be releasable and the pinion must be
manipulated. There are thus necessarily two independent manipulating
mechanisms.
The document GB-A-2.263.953 relates to a gear system which can consist in
one or two hard metal disks in which have been cut recesses of a shape
suitable for the intervals between chords (all equal in length), to form
circles of suitable selected radii, in which a movable toothed wheel or
pinion can be engaged by means of a selection mechanism with radial
sliding when the disk is in stationary position at the level of certain
points of alignment, called primary radii, thereby permitting a speed
selection and coupling loads to drive it. A combination of gear disks is
provided with a single conductive shaft, for rotation in a drill or the
propulsion of a bicycle, which ensures a wide range of speed change
(relative speed and torque), and the movement of rotation will be
transmitted from the disk having the recesses, which turn under the action
of pedals, to a toothed wheel secured to a squared or keyed shaft which
transmits the movement to a similar toothed wheel, located at the other
end of the shaft, which is in engagement, during its rotation, with the
disk having recesses, secured to the rear wheel, which propels the
bicycle.
In this case, clutching is ensured by the displacement of the pinion
relative to the plate at the level of the first radii, which are in fact
substantially radial grooves in the plate. There are three essential
drawbacks in this system. In the first place, there is wear of the teeth
of the pinion because of the translation of the level of the first radii.
Secondly, the time available to carry out the speed change is limited to
the time of engagement of the two adjacent teeth of the pinion. Thirdly,
the solidity and balance of the plate, which have two grooves at a precise
position, are not guaranteed.
The present invention provides simple and low volume mechanism which solves
the problems existing in the prior art.
SUMMARY OF THE INVENTION
The transmission according to the invention permits avoiding clutching of
the plate. Moreover, the teeth of the pinion are not subjected to any
translatory movement, the time available to carry out speed change is
equal to the period of rotation of a half-pinion, finally, the plate is
completely uniform, which is to say with grooveless recesses. This
transmission is hence more simple and more reliable.
To this end, the invention relates to a transmission comprising at least
one gear adapted to transmit rotary motion from a drive shaft to a driven
shaft, with variable speed ratio, the two shafts being not coaxial, one of
the shafts carrying a pinion, and the other shaft carrying a plate,
characterized by the fact that it is constituted, firstly of the pinion
axially split into two half-pinions movable axially relative to each other
and also relative to the shaft which supports them, the two half-pinions
being fixed in rotation relative to the shaft, secondly of the plate,
secured to the other shaft, comprising, on at least one of its surfaces,
several teeth, concentric to this shaft, which coact with the pinion, and
thirdly means for axially moving the two half-pinions so as to change the
engaged concentric teeth and thus the speed ratio.
The pinion comprises 2n teeth, each half-pinion comprising n teeth and each
concentric set of teeth of the plate comprising a multiple of n teeth, n
being a positive whole number.
The distance separating two adjacent teeth of the pinion, the two
half-pinions being in the same plane, is identical to the distance
separating two adjacent teeth of a same concentric set of teeth of the
plate.
The difference existing between the number of teeth of two concentric
adjacent sets of teeth of the plate is equal to n or to a multiple of n.
The plate comprises a region for changing concentric sets of teeth engaged
by the half-pinions, which is formed by alignments of two adjacent teeth
of each concentric set of teeth, the two alignments being parallel and
located on opposite sides of a radius of the plate, a so-called initial
radius.
In this change region, the distance separating two adjacent teeth of a same
alignment is constant.
According to one embodiment, the teeth of the pinion have a spherical
shape, and the teeth of the concentric sets of teeth are constituted by
the edges of transverse blind holes provided on at least one surface of
the plate.
According to a second embodiment, the teeth of the pinion have a spherical
shape, and the teeth of the concentric sets of teeth are constituted by
the edges of transverse bores provided in the plate.
In no matter what embodiment, the shaft, which carries the axially movable
pinion fixed in rotation relative to the shaft, is, in transverse
cross-section, channeled on at least the length of the shaft coacting with
the pinion, this form creating at least one groove ensuring the axial
mobility and the securement in rotation of each half-pinion of
complemental shape relative to said shaft.
Moreover, the H shape in transverse cross-section of the pinion shaft is
constituted by a square groove on two of its opposite surfaces.
On opposite sides of the plane formed by the pinion, said pinion is
prolonged in the form of two skirts of a shape complementary to the
subjacent shaft.
According to a modified embodiment, the pinion shaft is the drive shaft and
the plate shaft is the driven shaft.
According to another modification, the plate shaft is the drive shaft and
the pinion shaft is the driven shaft.
The axes of the shafts of the pinion and of the plate are perpendicular and
intersect.
In one embodiment, the plate coacts with at least one other pinion of
identical structure.
In an embodiment which uses two plates comprising blind holes side by side
and open at their free surfaces, the transmission is characterized by the
fact that at least one pinion coacts with one of the surfaces and at least
one other pinion coacts with the other surface.
According to a particular embodiment, wherein several pinions coact with
one plate provided with transverse bores, at least one pinion coacts with
one of the surfaces of the plate and at least one pinion coacts with the
other surface.
The use of a transmission as set forth above, is characterized in that,
upon change of engaged concentric tooth sets, the axial plane, defined on
the one hand by one of the half-pinions and on the other hand by the other
half-pinion, passes through the initial radius of the plate.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are given by way of indicative examples and are
not limiting. They show an embodiment according to the invention. They
permit easy comprehension of the invention.
FIG. 1 is a front view of the plate and of the profile of the pinion, the
two half-pinions coacting with a single concentric set of teeth of said
plate.
FIG. 2 shows a view identical to FIG. 1, but in which the half-pinions each
coact with a different concentric set of teeth, which is to say upon
change of ratio.
FIG. 3 is a cross-sectional view on the line A--A of FIG. 1.
FIG. 4 is a front view of the plate.
Finally, FIG. 5 shows a cross-sectional view on the line B--B of FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a new type of transmission 1, whose
principle is based on simplicity. Thus, this transmission 1 is solely
constituted by a gear, itself formed by a pinion 4 and a plate 7.
To permit rapid change of speed ratio, it is necessary that the plate
comprise a plurality of concentric recesses 8 to 14, and that the pinion 4
comprise displacement means permitting changing the ratio.
This pinion 4 is thus constituted by two half-pinions 5 and 6. These two
half-pinions are of identical shape and correspond to an axial split of
said pinion 4.
The displacement means are not described in the figures, they permit axial
displacement of the two half-pinions 5 and 6 relative to each other,
according to the arrow F3 in FIG. 2.
Pinion 4 and plate 7 are each secured to a shaft, respectively 3 and 2.
According to the embodiment shown in the figures, the shaft 2, associated
with the plate 7, constitutes a drive shaft. The shaft 3 itself is
associated with the pinion 4 and constitutes the driven shaft.
Nevertheless, it is entirely possible that the shaft 2 associated with the
plate 7 be the driven shaft and the shaft 3 associated with the pinion 4
be the drive shaft.
No matter what the embodiment, said pinion 4 and shaft 3 are movable in the
direction of the arrow F2 of FIGS. 1 to 3, and the plate 7 and the shaft 2
are movable in the direction of arrow F1.
The shafts 2 and 3 are in fact in p perpendicular position and their
longitudinal axes intersect.
So that the transmission of movement will be possible, the pinion 4 and the
plate 7 are provided with a multitude of teeth 15 and 16.
The teeth 15 of the pinion 4 have a spherical head to facilitate the
introduction of said teeth 15 into the transverse bores 16 whose edges
constitute the teeth 16 of the plate 7. This is clearly visible in FIG. 3.
In a particular embodiment shown in FIG. 5, the surface of the plate 7 is
beveled in a rounded manner at the level of the transverse bores 16, so as
further to facilitate the introduction of the spherical teeth 15 into the
bores 16.
Of course, the plate 7 could also be constituted by blind holes on one of
its surfaces or on its two surfaces, so that other pinions can be
implanted on the same surface or on the opposite surface to that which
already coacts with the pinion 4, as described. A plate 7, with transverse
bores 16, can also coact with several pinions 4 on its two surfaces.
So that all this transmission 1 can operate correctly, it is necessary that
certain characteristics be present.
Thus, in the drawings, the number of teeth 15 and 16, the dimensions,
distances and proportions are calculated to permit the good operation of
said transmission 1.
In the illustrated case, each half-pinion 5 or 6 comprises five teeth 15,
the pinion 4 having ten teeth. Of course, the axial split between the two
half-pinions 5 and 6 is between two teeth 15 and not across said teeth 15.
Concentrically with the shaft 2, the plate comprises concentric tooth sets
8 to 14. The innermost tooth set 8 comprises twenty transverse bores 16.
The adjacent and next outer set of teeth 9 comprises fifteen, and so on
with the tooth set 10 having thirty recesses bores, the set of teeth 11
having thirty-five recesses, each adjacent tooth set comprising a number
of bores 16 greater than five to the outermost tooth set.
This number five corresponds to the number of teeth 15 of each half-pinion
5 or 6. There could nevertheless be a different number, but which however
would be a multiple of five, which is to say ten, fifteen, twenty, etc.
The only mechanical requirement resides in the fact that the plane passing
through the split between the two half-pinions 5 and 6, must pass through
the initial radius 18 of the region 17 for changing the ratio of the plate
7, as will be explained further hereinafter.
Of course, the distance which separates two teeth 15, when the two
half-pinions 5 and 6 are coplanar, is identical to the distance which
separates two adjacent bores 16 of a same concentric tooth set 8 to 14. In
connection with H this, if FIGS. 2 and 4 show a plate 7 having four
concentric tooth sets 8 to 11, said plate can be of greater diameter to
receive other tooth sets 12 to 14, as is the case in FIG. 1, in which five
other tooth sets 12 to 14 are schematically shown in phantom view.
It is evident that the number of teeth 15, bores 16 and tooth sets 8 to 14
is not limited. It is possible to provide transmission 1 having a
different base number than five.
To permit good sliding of the half-pinions 5 and 6, upon ratio change (in
FIGS. 2 and 4, there is a transmission with four ratios and four or nine
ratios in FIG. 1), along the shaft 3, the latter shaft 3 comprises, at the
level of the change region 17, a structural modification comprising
longitudinal grooves 19, which are shown in transverse cross-section in
FIG. 3 and are disposed on opposite surfaces of a square, such that the
shaft 3 in transverse cross-section is of channeled form, and more
precisely of a H shape, whilst outside the region 17, said shaft 3 is of
conventional shape, which is to say round. The half-pinions 5 and 6
therefore have a shape that is complementary and cooperate each with a
portion of each groove 19. In FIG. 1, in which the number of concentric
teeth sets 8 to 14 is nine, the grooves 19 are longer than in FIG. 2, in
which the number of concentric tooth sets 8 to 11 is four.
Moreover, further to improve the guidance in sliding of the half-pinions 5
and 6 relative to each other and relative to the shaft 3, said
half-pinions 5 and 6 are prolonged along the grooves 19 in the form of
skirts 20.
As to the movement of the half-pinions 5 and 6 in the direction of arrow
F3, this is rendered possible by any electromechanical apparatus known to
the public which will be sufficiently precise and rapid to permit the
offset of one of the half-pinions 5 or 6 relative to the other 6 or 5 upon
rotation by one half-turn on itself of the pinion 4 in the direction of
the arrow F2.
The procedure for ratio change is therefore as follows.
The importance of the ratio change region 17 of the plate 7 should now be
noted. In this region 17, all the concentric tooth sets 8 to 11 are
positioned such that the bores 16, of all the tooth sets 8 to 11, situated
to the right of the initial radius 18, will be disposed one behind the
other according to a straight line which is parallel to said initial
radius 18. This is also true for the bores 16 located to the left, such
that the ratio change region 17, the distances between the adjacent bores
to the right or to the left of the radius 18 of the different concentric
tooth sets 8 to 11 are constant.
The operation is hence as follows.
When there is no ratio change, the pinion 4 behaves like a normal pinion,
which is to say that the two half-pinions remain coplanar.
When a ratio change is required, either manually or automatically the
pinion 5 or 6, which is not engaged in a region which is a so-called
pre-ratio change region 21, delimited on the one hand by a line 23 and on
the other hand by the initial radius 18, will be displaced such that its
plane will be tangent to the selected concentric tooth set 8 to 11. At
said initial radius 18, one of the half-pinions 5 or 6 will coact with the
former tooth set 8 to 11 at the region 21, whilst the other half-pinion 5
or 6 will coact with the new tooth set 8 to 11 which has been selected, in
a post-ratio change region 22, delimited by a line 24 and the initial
radius 18. In this region of ratio post-change 22, the half-pinion 6 or 5,
which is no longer engaged, will then return to the plane constituted by
the other half-pinion 5 or 6, engaged with the new tooth set 8 to 11, and
hence with a new multiplication ratio.
REFERENCES
1. Transmission
2. Drive shaft
3. Driven shaft
4. Pinion
5. First half-pinion of pinion 4
6. Second half-pinion of pinion 4
7. Plate
8 to 14. Concentric tooth sets of plate 7
15. Teeth of pinion 4
16. Teeth or transverse recesses of the plate 7
17. Ratio change region of the plate 7
18. Initial radius
19. Longitudinal grooves of the shaft 3
20. Skirts
21. Ratio pre-change region
22. Ratio post-change region
23. Pre-ratio change line
24. Post-ratio change line
F1. Movement of rotation of the shaft 2 and of the plate 7
F2. Movement of rotation of the shaft 3 and of the pinion 4
F3. Axial displacement of the two half-pinions 5 and 6 relative to each
other and relative to the shaft 3
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